Vaulted chamber, Leiden University Library

With its unique collection of books and other sources, Leiden University Library, founded in 1575, is regarded as one of the centres of the Enlightenment. Today, its holdings include approximately 5,200,000 books, 1,000,000 e-books, 20,000 current serials, 40,000 e-journals, 60,000 Oriental and Western manuscripts, 500,000 letters, 100,000 maps, 100,000 prints, 12,000 drawings and 300,000 photographs. This is rather more than would fit into the vault room at Rapenburg 73, shown here in a photograph taken in 1940, which was the library's site from 1587 to 1595.

Vaulted chamber (Gewelven kamer), Leiden University Library, black-and-white photograph, Leiden, 1940, unknown photographer; source: Rijksdienst voor het Cultureel Erfgoed, rijksmonument number 2464, http://beeldbank.cultureelerfgoed.nl/afbeelding/20135437, Wikimedia Commons, http://commons.wikimedia.org/wiki/File:Gewelven_kamer_-_Leiden_-_20135437_-_RCE.jpg.  CC BY-SA 3.0 NL Deed / Attribution-ShareAlike 3.0 Netherlands, http://creativecommons.org/licenses/by-sa/3.0/nl/deed.en.